Voltage regulating system



7, 1937. c. J. KETTLER El AL VOLTAGE REGULATING SYSTEM Filed July 9,1936 3 Sheets-Sheet l Figl.

on VJ i rt r t O teO t nK t W [M mmm nv h ee T

Aug. 17, 1937.

c. J. KETTLER ET AL 2,090,516

VOLTAGE REGULATING SYSTEM Filed July 9, 1936 5 Sheets-Sheet 2 y am 1rAtt orney.

Aug. 17, 1937.

c. J. KETTLER ET AL 2,090,516

VOLTAGE REGULATING SYSTEM 3 Sheets-Sheet 3 Filed July 9, 1936 Inventors:Clarence d. Kettler: Levin W. Foster,

a. (9w by Attorney.

Patented Aug. 17, 1937 UNITED STATES,

PATENT OFFICE vonmoa nnoum'rmc srs'ram Clarence J. Kettler and Levin W.Foster, Pittsiield, Mesa, assignors to General Electric Company. acorporation of New York Application July 9, 1936, Serial No. 89,746 10Claims. (01. 171-419 10 ers, electric valve means have been employed tocontrol the interconnection of the associated circuits through theterminals of the transformer windings. In certain of the prior artarrangements, the electric valve means have been con- 15 trolled inaccordance with the voltages of the associated circuits to effectselective energization of the electric valve means to control therelative voltages of the circuits. There has been a decided need forimproved voltage regulating systems of the type employing electric valvemeans which will effect the desired selective energization of thevarious associated electric valve means in accordance with an electricalcondition of the associated circuits and which will accom- 95 plish asmooth and precise transfer of load current among the electric valvemeans.

It is an object of our invention to provide a new and improved electricvalve voltage regulating system fbr use in connection with a multi- 30terminal transformer, whereby the transfer of load current among thevarious electric valve means is accomplished in a precise and reliablemanner in accordance with an electrical condition of one of theassociated circuits.

It is another object of our invention to provide an electric valvevoltage regulating system to be used in connection with multi-terminaltransformers whereby the transfer of the load current among the variouselectric valves is ef- 40 fected in accordance with the voltage of oneof the associated circuits and in which the excitation circuits for thevarious electric valve means are arranged so that the load transfer iseffected when the instantaneous value of the load current 45 issubstantially zero.

In' accordance with the illustrated embodiments of our invention, weprovide new and improved electric valve voltage regulating systems ofthe type adapted to be used in connection with multi-terminaltransformer windings in which the voltage control is effected by theselective energization of the various electric valve means to controlthe relative voltages of the associated circuits. Electric valve meansincluding pairs of electric valves, reversely connected in parallel,

are connected to the various terminals of the associated transformerwindings and are employed to connect selectively the transformerterminals to one of the associated circuits to accomplish the desiredvoltage control. A plu- 5 rality of excitation'circuits, each associatedwith a diiferent pair of electric valves, serve to control theenergization of the electric valves to render them conductive to effectthe transfer of current in both directions through the transformerwinding. Current responsive means, such as reactors or resistors, areconnected in series relation with each pair of electric valves to effecttransfer of the load current among the various electric valve means whenthe instantaneous value of the load current is substantially zero. Theexcitation circuits are controlled in accordance with an electricalcondition, such as the voltage of one of the associated circuits. Forexample, a contact making voltmeter may be employed to effect theselective energization and deenergizationof electric valve means inorder to accomplish the desired transfer in load current. The currentresponsive means control the excitation circuits so that only theelectric valve means associated with one of the transformer terminalsare rendered conductive at any one time and are arranged so that eventhough the contact making voltmeter dictates a load transfer, thistransfer will not be effected until the instantaneous value of theloadcurrent is substantially zero. In a modified embodiment of ourinvention, phase shifting means are interposed between the currentresponsive means and the excitation circuits to introduce in theexcitation circuits potentials which are substantially 180 electricaldegrees out of phase with the potentials impressed on the anodes of theelectric valves to which the transfer is to be made. In this manner theexcitation circuits are controlled to assure that the transfer will bemade at exactly the time when the instantaneous value of theload currentis zero.

For a better understanding of our invention, reference may be had to thefollowing descrlption taken in connection with the accompanying drawingsand its scope will be pointed out in the appended claims.

Fig. 1 of the accompanying drawings diagrammatically represents anembodiment of our invention in which the transfer of the load currentbetween various terminals of a multi-terminal transformer winding isaccomplished in accordance with an electrical condition of an associatedcircuit. Figs. 2 and 3 diagrammatically show modified arrangements in.which electric valve means, of the type employing immersion-ignitorcontrol members, control therelative voltagesof the associated circuitsin accordance with an 6 electrical condition of one of the circuits.

Referring to Fig. 1 of the accompanying drawings, our invention isdiagrammatically shown as applied to a voltage regulating system. Analternating current supply circuit I is employed to energize analternating current load circuit 2 through a transformer '3 including aprimary winding 4 having voltage controlling terminals 5 and 6. Electricvalve means including electric valves I and 8, which are reverselyconnected in parallel, are associated withterminal 5, and electric valvemeans including electric valves 9 and I9, also reversely connected inparallel, are associated with terminal 6 of transformer winding 4. Theelectric valves 7, 8, 9 and II] are preferably of the type employingionizable mediums, such as gases or vapors, and each includes an anodeII, a cathode I2 and a control member I3. Shortcircuiting switches I4and I5 are connected to shunt electric valves 1 and 8, and 9 and I0, re-

spectively, when tap changing functions are not being performed by theseelectric valves. Excitation circuits I6 and I! are employed to controlthe energization of electric valves I and 8, and 9 and I0, respectively.Considering excitation circuits I6 in particular, ,a transformer I8having primary windings I9 and 29 and secondary windings 2I serves torender the electric valves I and 8 alternately conducting so thatcurrent may be transferred in both directions through the lefthandportion of primary winding 4 of transformer circuits I6 and I1. Currentlimitating resistances 23 are connected in series with the controlmembers I3 of electric valves I, 8, 9 and I9. In order to controlselectively the energization of excitation circuits I6 and I! inaccordance with 5 an electrical condition, such as the voltage of theload circuit 2, we employ any suitable arrangement such as a voltageresponsive means 24 including an actuating winding 25, a spring biasedplunger 26, a movable contact member 21 and stationary contacts 28 and29. The stationary contact 28 is employed to effect energization ofexcitation circuit I6 and the stationary contact 29 is arranged toeffect energization of excitation circuit I1. A transformer 39 connectsthe alternating current load circuit 2 to the voltage responsive means24. While we have shown the voltage responsive means 24 as beingenergized from the alternating current load circuit 2, it should beunderstood that the voltage responsive means may be connected to thealternating current supply circuit I to effect control of the system inaccordance with the voltage of the supply circuit I.

To provide a means for effecting transferof the load current betweenterminals 5 and 6 when the instantaneous value of the load current issubstantially zero, we employ current responsive means such asresistances 3| and 32 which are connected in series relation withelectric valves I and 8, and 9 and I0, respectively. A voltage whichvaries in accordance with the voltage appearing across the resistance 3|is introduced in the excitation circuit I! by means of primary winding20 of transformer I8 and is correlated in phase so that the excitationcircuit I'I maintains electric valves 9 and I9 non-conducting so long asthe electric valves I and 8 are conducting current, even though thevoltage responsive'means 24 dictates a transfer of load current fromelectric valves I- and 8 to electric valves 9 and I0. In like manner, avoltage which varies in accordance with the voltage appearing acrossresistance 32 is introduced in excitation circuit 16 through primarywinding 20 of transformer I8 to maintain electric valves I and 8non-conducting so long as electric valves 9 and III are conductingcurrent and this controlling action is maintained even though voltageresponsive means 24 dictates a transfer from electric valves 9 and ID toelectric valves 1 and 8.

While in Fig. l of the accompanying drawings we have diagrammaticallyshown our invention as applied to a transformer tap changing arrangementin which the transformer is provided with only two terminals, it shouldbe understood that our invention may be applied to electric valvetransformer tap changing circuits in which any number of terminals areused.

The general principles of operation of the embodiment of our inventiondiagrammatically shown in Fig. 1 may be best explained by consideringthe voltage regulating system when the primary winding 4 of transformer3 is being energized from the alternating current circuit I throughelectric valves 9 and I9. Let it be assumed that the voltage responsivemeans 24 is adjusted to maintain a predetermined range of voltages ofthe alternating current load circuit 2 and let it be further assumedthat the load current in the circuit 2 has increased so that the voltageof the circuit 2 has decreased below the predetermined minimum value.Under these conditions, the spring biased plunger 26 of voltageresponsive means 24 will have been moved to the position shown in Fig. 1of the drawings to dictate an increase in the voltage of the loadcircuit 2. By virtue of the fact that the movable contact member 2'! isplaced in engagement with stationary contact 28, the primary winding I9of transformer i B in excitation circuit. I6 will be energized, tendingto render electric valves 1 and 8 conductive. However, excitationcircuit I6 will not render electric valves 1 and 8 conductive until thevalue of current conducted by electric valves 9 and I0 is substantiallyzero by virtue of the fact that the voltage introduced in excitationcircuit I6 by means of primary winding 29 of transformer I8 tends torender ineffective the potential introduced in this circuit by primarywinding I9. When the current conducted by electric valves 9 and I0passes through zero,

excitation circuit I6 will render electric valves I and 8 conductive sothat the voltage of supply circuit I is impressed between the left-handterminal of primary winding 4 and terminal 5 of transformer 3 to eiT-ectthe desired increase in the voltage of alternating current load circuit2. On the other hand, if the voltage of the alternating current loadcircuit 2 increases to a value greater than the predetermined maximumvalue for which the voltage responsive means 24 is adjusted, the springbiased plunger 26 will be actuated so that the movable contact member 21engages the stationary contact 29 to impress in primary winding I9 oftransformer I8 in excitation circuit I! a potential tending to renderelectric valves 9 and I9 conductive. The voltage introduced inexcitation circuit I! by means of the resistance 3| and the primarywinding 29 will plied to an electric valve voltage regulating system inwhich electric valves of a type employing immersion-ignitor controlmembers are used. An alternating current supply circuit 33 energizes atransformer 34 having a secondary winding 35 and an extension 35 to thesecondary winding which is inductively associated with the secondarywinding 35. An alternating current load circuit 36 is arranged to beenergized from the lower terminal of the secondary winding 35 and theupper terminal of extension winding 35. The extension winding 35' of thesecondary winding is provided with electric terminals or taps 31, 38,39, 46 and 4| and associated switching means 42 and 43. Electric valves44, 4s, 4s and 41, of the type employing immersion-ignitor controlmembers and each including an anode 48, a mercury pool cathode 46 and animmersion-ignitor control member 56, are electrically interposed betweenthe secondary winding and the extension 35' of secondary winding 35 tocontrol selectively the voltage of the alternating current load circuit36. Electric valves 44 and 45, and 46 and 41, respectively are reverselyconnected in parallel so that alternating current may be conductedthrough the secondary winding 35 andextension winding 35'. Switches 5|and 52 are connected to short circuit the electric valves 44 and 45, and46 and 41, respectively, to eliminate the arc-drop incldent to dischargethrough these electric valves when the electric valve system is notbeing employed in a tap changing operation.

.In order to control the conductivity of electric valves 44, and 46, 41,excitation circuits 53 and 15 54 respectively serve to render theelectric valves of each group alternately conductive. Each of theexcitation circuits 53 and 54 includes a transformer 55-having a primarywinding 56 and secondary windings 51. Referring in particular toexcitation circuit 53, the lower secondary winding 51 is associated withthe immersion-ignitor control member 56 of electric valve 44 andsupplies pulses of unidirectional-current to this control member througha unidirectional conducting device 58. Similarly, the upper secondarywinding 51 of. transformer 55 is associated with the control member 56of electric valve 45 and periodically renders the valve 45 conductive bysupplying a pulse of unidirectional current through 60 theunidirectional conducting device 59. In similar manner, the secondarywindings 51 of transformer 55 in excitation circuit 54 control theconductivity of electric valves 46 and 41. A suitable source ofalternating potential 66, preferably of the same frequency as that ofthe alternating current supply circuit 33, impresses alternatingpotentials on the primary windings 63 and 64 of transformers 6| and 62,respectively. A voltage responsive means 65 selectively energizes theprimary windings 63 and 64 of transformers 6| and 62 in accordance withthe voltage of the alternating current load circuit 36 to control theelectric valve tap changing system to energize the various groups ofelectric valves associated with the diiferentterminals of the extensionwinding 36'.

To provide a voltage which varies in accordance with the currentconducted by electric valves 4441., we employ current responsive meanssuch as reactors 66 and 61 which are connected in series relation withelectric valves 44 and 45, and 46 and 41, respectively, and which areinterposed between these pairs of electric valves and the extensionwinding 36'. Phase shifting circuits 66 and 66, having capacitances 16and 1| and variable resistances 12 and 13, respectively, are interposedbetween the reactors 66 and 61 and excitation circuits 53 and 64 tomodify the phase of the potential introduced into the excitationcircuits 53 and 54. The reactor 66 and the phase shifting circuit 66 arearranged to introduce in the excitation circuit 54, through atransformer 14 having a primary winding 15 and a secondary winding 16, apotential which is substantially electrical degrees out of phase withthe potential impressed on the control members 56 of electric valves 46and 41. By virtue of the fact that this potential exists only so long ascurrent is conducted through the reactor 66, this 180 electrical degreedisplaced potential will be present in the excitation circuit 54 onlyduring the interval when current flows in electric valves 44 and 45. Animpedance 11 having a negative impedance-current characteristic, such asthe material disclosed and claimed in U. S. Patent 1,822,742 grantedSeptember 8, 1931 on an application of K. B. McEachron and assigned tothe assignee of the present application, is connected across thesecondary winding 16 of transformer 14 to suppress high voltagetransients which may be introduced into the excitation circuit 54 byvirtue of current disturbances in the alternating current load circuit36. The reactor 61 and the The operation of the embodiment of ourinvention diagrammatically shown in Fig. 2 may be best explained byassuming that electric valves 46 and 41 are conductive to impress on thealternating current load circuit 36 a potential through switch 43 andtap 36 of extension winding 35'. If it be assumed that the potential ofthe alternating current circuit 36 has decreased to a value less thanthe predetermined minimum value for which the voltage responsive device65 has been adjusted, the device 65 will have been moved to the positionshown in the figure to remove the potential impressed on primary winding64 of transformer 62 and to impress a potentlal on primary winding 63 oftransformer 6|. This potential tends to energize excitation circuit 53and thereby effect energization of control members 56 of electric valves44 and 45. However, the potential incident to the flow of currentthrough reactor 61 is introduced in excitation circuit 53 through thephase shifting circuit 66 and transformer 18 to render ineffective thepotential introduced in the excitation circuit by the transformer 6|. Bythe proper adjustment of the resistance 13 of phase shifting circuit 66,the potential introduced into the excitation circuit 53 may be made tobe in exact phase opposition to the potential introduced into thecircuit by transformer 6!. If the circuit 66 is connected to beenergized from the alternating current supply circuit 33, or from acircuit having a potential exactly in phase with the alternating currentcircuit 33, electric valves 44 and 45 will be maintained non-conductiveuntil the instantaneous value of the current flowing through the reactor61 is substantially zero. At

that instant the potential introduced in excita-.

5 tion circuit 53 by transformer 6| will become effective to alternatelyenergize control members 50 of electric valves 44 and 45 to connect theload circuit 36 to terminal 31 of extension winding 35, therebyeffecting an increase in the potential of 10 the alternating currentcircuit 36.

By the proper adjustment of the constants of the phase shifting circuits68 and 69, the transformer tap changing system may bearranged to operateunder any particular power. factor conditions. In order to operate mostsatisfactorily, these circuits should'be adjusted for the \rnost laggingpower factor condition.

In a similar manner, when the voltage of the alternating current circuit36 increases above a.

predetermined value, the electric valve voltage controlling system willbe effective to transfer the load current from the electric valves 44and 45 to electric valves 46 and 41 at the time when the instantaneousvalue of the load current is substantially zero.

Fig. 3 of the accompanying drawings diagrammatically represents amodified embodiment of our invention which is quite similar inconstruction and arrangement to that shown in Fig; 2,

differing only in regard to the type of excitation circuit employed, andcorresponding elements have been assigned like reference numerals. InFig. 3 excitation circuits 19 and 88 of the impulse type are associatedwith electric valves 44, 45 and 46, 41, respectively. The excitationcircuits I3 and 80 are similar in construction and arrangement.Referring to excitation circuit 13 in particular, control electricvalves 8| and 82, preferably of the type employing ionizable mediums,are associated with electric valves 44 and 45, respectively, and serveto supply impulses of current to control members 50 of these valves. Toprovide means for supplying impulses of current, we provide an impulsetype of excitation 45 circuit including capaeitances 83 which arecharged from a suitable source of alternating current 84 through atransformer 85 having a primary winding 86 and secondary windings 81 and88. Unidirectional conducting devices 89 are connected between oneterminal of the capacitances 83 and transformer secondary windings 81and 88, to charge the upper plates of capacitances 83 positive relativeto the lower plates. Control electric valves 8| and 82 are renderedconductive at the proper time by means of a transformer 90 havingaprimary winding 9| and secondary windings 92. The primary winding 9| oftransformer 90 in excitation circuit 19 is connected in series relationwith the secondary winding of transformer 18 and the secondary windingof transformer 6|, so that the potential impressed on the primarywinding 9| is the resultant of the potential introduced in this circuitby means of transformer 18 and transformer 6|.

The operation of the embodiment of our invention shown in Fig. 3 issubstantially the same as that described above in connection with thearrangement shown in Fig.- 2, differing only in the manner in which theimpulse excitation circuits 19 and 86 of Fig. 3 effects energization ofthe immersion-ignitor control members 50 of electric valves 44--4|. Letit be assumed that the electric valve voltage regulating system isoperating so that a voltage is being impressed on the alternatingcurrent load circuit 36 through electric valves 46 and 41, switch 43 andterminal 38 of extension winding 35. When the voltage of circuit 36decreases below a predetermined minimum value, the voltage responsivedevice 65 will be moved to the position shown in Fig. 3, introducing inexcitation circuit 19 through transformer 6| a potential tending torender control electric valves'8l and 82 conductive. .When theinstantaneous value of the current through electric valves 46 and 41 issubstantially zero, the potential introduced in excitation circuit 13will be effective to render control electric valves 8| and 82conductive, thereby permitting the capacitances 83 to discharge throughthe immersionignitor control members 50 of electric valves 45 in theproper predetermined order. In this manner, the time at which thecontrol electric valves 8| and 82 are rendered conductive will bedelayed until the instantaneous value of the current through electricvalves 46 and 41 is zero. The phase shifting cicuits 68 and 69 by theproper adjustment for the most lagging power factor .condition of theload imposed on load circuit 36, will impress potentials in substantialphase opposition to the potentials introduced in excitation circuits 19and by the transformers 6| and 62, so that both groups of electricvalves will not conduct at the same time.

While we have shown and described our invention as applied to aparticular system of connections and as embodying various devicesdiagrammatically shown, it will be obvious to those skilled in the artthat changes and modifications may be made without departing from ourinvention, and we, therefore, aim in the appended claims to cover allsuch changes and modifications as fall within the true spirit and scopeof our invention.

What we claim as new and desire to secure by Letters Patent of theUnited States, is:

1. In combination, a supply circuit, a load circuit, electric.translating apparatus interposed between said circuits comprising aplurality of electric valve means for controlling the relative voltagesof said circuits, means responsive to the voltage of said load circuitto effect transfer of the load current among said electric valve means,and means associated with each of said electric valve means formaintaining the other of said electric valve means nonconducting whileone of said electric valve means is conduct- 3. In combination, analternating current supply circuit, an alternating current load circuit,means interposed between said circuits comprising a transformer windinghaving a plurality of electrically spaced terminals, electric valvemeans associated with each of said terminals for controlling therelative voltages of said circuits, a plurality of excitation circuitseach associated with a different one of said electric valve means forcontrolling said electric valve means,

and current responsive means for controlling said excitation circuits tomaintain the other of said electric valve means non-conducting when oneof said electric valve means is conducting. 4. In combination, analternating current supply circuit, an alternating current load circuit,means interposed between said circuits comprising a transformer windinghaving a plurality of electrically spaced terminals, electric valvemeans associated with each of said terminals for controlling therelative voltages of said circuits, a plurality of excitation circuitseach associated with a different one of said electric valve means forcontrolling the conductivity of the associated electric valve means, anda plurality of current responsive means each associated with a differentone of said electric valve means for controlling said excitationcircuits to maintain the other of said electric valve meansnon-conducting when 20 one of said electric valve means is conducting.

5. In combination, an alternating current supply circuit, analternating'curren't load circuit, means interposed between saidcircuits comprising a transformer winding having a plurality of 25electrically spaced terminals, a pair of electric valve means associatedwith each of said terminals for controlling the relative voltages ofsaid circuits, said pairs of electric valve means being reverselyconnected in parallel, a plurality of excitation circuits eachassociated with a different pair of said electric valve-means forcontrolling the conductivity of said associated electric valve means,and means connected in series relation with each of. said pairs ofelectric valve means for maintaining the other pairs of said electricvalve means non-conducting when one pair of said electric valve means isconducting.

6. In combination, an alternating current supply circuit, an alternatingcurrent load circuit, means interposed between-said circuits comprisinga transformer winding having a plurality of electrically spacedterminals, electric valve means associated with each of said terminalsfor con-- trolling the relative voltages of said circuits, a pluralityof excitation circuits each associated with a different one of saidelectric valve means for controlling the conductivity of said associatedfect said transfer only when the instantaneous value of the load currentis substantially zero.

7. In combination, a supply circuit, a load circuit, electrictranslating apparatus interposed be- 00 tween said circuits comprising aplurality of electric valve means for controlling the relative voltagesof said circuits, each of said electric valve means including a pair ofarc discharge paths of the type employing immersion-ignitor control 65members and being reversely connected in parallel, means responsive toan electrical condition of one of said circuits to effect transfer ofthe load current among said electric valve means, a plurality ofexcitation circuits each associated 70 with a different one of saidelectric valve means with the other of said electric valve means toeffor energizing said control members, and means associated with each ofsaid electric valve means for controlling said excitation circuits tomaintain the other of said electric valve means nonconducting when oneof said electric valve means is conducting.

8. In combination, a supply circuit, a load circuit, electrictranslating apparatus interposed between said circuitscomprising aplurality of electric valve means for controlling the relative voltagesof said circuits, a plurality of excitation circuits each associatedwith a different one 01' said electric valve means for controlling theconductivity of said electric valve means, a plurality of currentresponsive means each connected in series relation with a different oneof said electric valve means for controlling the associated excitationcircuits to maintain the other of said electric valve meansnon-conducting when one of said electric valve means is conducting, andmeans interposed between said current responsive means and saidexcitation circuits for controlling said excitation circuits to effect atransfer of the load current among said electric valve means when theinstantaneous value of said load current is substantially zero.

9. In combination, a supply circuit, a load circuit, electrictranslating apparatus interposed between said circuits comprising aplurality of electric valvemeans for controlling the relative voltagesof said circuits, a plurality of excitation circuits each associatedwith a different one of said electric valve means for controlling theconductivity of said electric valve means, control means responsive toan electrical condition of one of said circuits for controlling saidexcitation circuits to effect transfer of the load current among saidelectric valve means, and means responsive to the current conducted byeach of said electric valve means for introducing potentials in theexcitation circuits of the other of said electric valve means to rendersaid control means inefl'ective until the instantaneous value of saidload current is substantially zero.

10. In combination, a supply circuit, a load cirtween said circuitscomprising a plurality of v cuit, electric translating apparatusinterposed beelectric valve means for controlling the relative voltagesof said'circuits, a plurality of excitation circuits each associatedwith a different one of said electric valve means for controlling theconductivity of said electric valve means, means responsive to anelectrical condition of one of said flrst mentioned circuits to effecttransfer of the substantially zero.

CLARENCEJ. KE'ITLER. LEVIN W. FOSTER.

